Definition - What does Lock Screen mean?
Lock screen is a feature introduced in Microsoft’s next-generation Windows 8 operating system. The lock screen includes two components: a lock screen background image with dynamic battery status, network icons, and message icons, and a login screen for entering a password and gain access to the system. The lock screen feature is optimized for both tablets and PC users.
The lock screen feature of Windows 8 looks akin to the lock screen of the Windows Phone OS.
Techopedia explains Lock Screen
Unlike Windows XP, Windows Vista and Windows 7, Windows 8 requires the lock screen feature because it can be used in touch screen environments. One of the interesting aspects of the lock screen feature is that it displays notification with respect to a specific task. The user may choose to configure the notifications to be sent from all supported applications or only from the required applications from the list. In addition, Windows 8 allows users to personalize the lock screen background without the use of third-party utilities.